Insect forecast exhibits pest potential

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Wheat mosquitoes and wheat stalk saw blades are among the crop pests likely to cause problems in Alberta this year, according to recently released data and maps from the Alberta Insect Pest Monitoring Network.

Although nothing replaces personal field monitoring or “boots in the field,” as the network regularly notes, projections based on a fall 2020 survey could show that wheat mosquitoes are particularly prevalent in central Alberta east of Edmonton and areas west and south of Edmonton City could be a problem.

“Growers in this area should consider mosquito-tolerant wheat and other integrated pest control (IPM) strategies to minimize this risk,” advised the network. “The wheat mosquito in both areas will continue to be a problem in individual fields, especially if sowing is late and there is above-average rainfall in spring.”

The risk is low in southern Alberta and the Peace River region, the forecast said. In the latter case, however, there are “enough mosquito populations to encourage resurgence when conditions are favorable for the insects,” the network said.

Delayed harvests and higher than normal rainfall in the region would increase the likelihood of problems.

Data on the development of the prognosis were obtained from 311 field samples from 64 counties that were checked for larvae cocoons.

In the coming harvest season, “growers should plan to monitor their fields when the adult mosquitoes are flying and their wheat is at the vulnerable stage. In all areas of the province, producers are asked to monitor their wheat fields for the presence of adult mosquitoes from the head of wheat emergence to anthesis. “

A species of wasp called macroglens penetrans can parasitize wheat mosquitoes and has historically helped reduce mosquito numbers, the network says. The wasps are best suited to warm, dry conditions.

Once the wheat mosquito has established itself, it is unlikely to go away. It can survive in low-lying and moist field areas and can survive for a period of time even under adverse conditions. On the other hand, a small number of mosquitoes also sustain the life of natural enemies who can fight when the number increases.

Wheat log saw blade projections show county Forty Mile in southern Alberta is again at higher risk, based on evidence from field surveys in the fall of 2020.

“Overall, the risk of sawflies remains lower than it was in the early 2000s, but the increased damage to sawflies in many parts of southern Alberta signals a resurgence due to drier conditions in recent years,” the network said.

Planting hard-stemmed varieties of wheat can thwart the pest.

Nevertheless, saw blades can migrate from the stubble of the previous year into a harvest. A parasitic wasp called Bracon cephi has helped reduce populations in the past.